Control systems to control hydraulic pumps are well known. In hydraulic systems with open or closed loop circuits, the working pressure is limited by pressure relief valves which are supported by pressure override or pressure limiter systems. The pressure override or pressure limiter systems control the oil flow of a variable hydraulic pump in a hydraulic circuit in a way that the pressure energy of a minimum oil flow is converted into heat. The oil flow from the pressure relief valve to control maximum pressure imported will through a check valve on the other side of the circuit keep the mass of oil inside the circuit at a constant value. These systems with pressure override or pressure limiter functions are used in a variety of applications where the probability exists that at high power conditions a high amount of pressure energy of a relatively large oil flow is converted into heat. Therefore based on quick temperature rise, excessive heat energy will be dissipated, resulting finally in overheating and damage of the units.
Therefore, a principal object of the invention is to provide a control system for a variable hydraulic pump and a control process for the same, whereby in high power conditions the pressure energy converted into heat will be minimized with a simple system design.
This and other objects will be apparent to those skilled in the art.